Apparatus for placing explosives



April 28, 1942. c. MacDoNALD APPARATUS FOR PLACING EXPLOSIVES Filed Nov. 3, 1939 ExPLoslvE 73 72 :5 ExPLosxvr;

EXPLOSIVE Patented Apr. 28, i942 APPARATUS FOR PLACING EXPLOSIVES Gordon C. MacDonald, Tulsa, Okla., assignor tof Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania "Application November 3, 1939, serial 10.302357 (c1. 1oz-4) Claims.

This invention or discovery relates to apparatus for placing explosives, and it comprises 'an apparatus for placing a charge of explosive at any desired level in a well, including an explosive container, cable means for lowering the container in a well, electrically operable releasing means associated with the container and `adapted upon operating thereof to release the explosive in the Well, and means for applying electrical energy to said releasing means; all as more fully hereinafter set forth and as claimed.

In the oil production art it is often desirable or necessary to shoot a well, after drilling is completed. to shatter Athe rock surrounding the well bottom and thereby open up channels for the oil. For this purpose heavy charges of nitroglycerine are ordinarily used. These are deposited in the well and exploded by a time bomb or other suitable means. The present apparatus for placing the explosive permits lowering a con-v tainer shell of explosive to the bottom with the aid of a hookA or similar attachment which releases the shell automatically when the shell reaches the bottom of the well and takes the weight of the shell off the hook. Ordinarily several shells are used, lowered successively one on top oi another. Sometimes the explosive is lowered in a dump shell and is released directly into the well. In practice, the releasing mechanism sometimes fails to function, which necessitates raising the loaded shell and making adjustment. This is dangerous especially when the explosive has been subjected to high temperatures in the `lower part of the well, thereby making it more sensitive to shock. Also there is considerable strain put upon the reel, lowering line, etc.

On the other hand, in this conventional system the shell is often releasedprematurely. .Since the arrangement is such that the shell is released upon any bottom contact such as to relieve the weight on tlre releasing mechanism, the explosive may become released at the wrong place by the shell striking floating or suspended material in the bore liquids. Sometimes the borewalls cave after a portion or the explosive has been placed, and the rst evidence of this is the impact of the subsequent shell upon the caved material with resulting deposition of the explosive at that point. Removal is hazardous. 1

Similar considerations apply to the dump shell explosive-placement system, with even greater force, since once the explosive is released from the shell, it cannot be recovered.

The present invention is based on the discovery that by a suitable electrical control, actuable lll from the top of the well, explosive can be released at any desired level in a well and premature releast can be obviated.

Among the objects of the present invention are the provision of an improved apparatus for placing explosive at a desired level in a well, in which release of explosive is accomplished under a positive electrical control, and the provision of such apparatus in which accidental release of explosive at a level above the desired level is made impossible.

The invention can be embodied in two principal forms, adapted for release of a. shell of explosive, and for release of free explosive into the well. The apparatus includes an electrically actuable releasing device, arranged for lowering into a well on a cable and, upon actuation, to release either a shell of explosive, or a charge of free explosive as the case may be. Electrical means are provided at the surface for operating the release. Means are provided for positively retaining the explosive charge until the electrical release is actuated.

In the accompanying drawing there are shown diagrammatically several vexamples of specic embodiment of apparatus within the purview of the invention and adapted for the performance of the method. In the drawing,

Fig. 1 is a diagrammatic view of the complete apparatus as set up at a well,

Fig. 2 isa detail view in central vertical section, with some parts shown in elevation, of one .form of explosive shell releasing means,

Figs. 3 and 4 are similar views of two modified forms of the apparatus of Fig. 2,

Fig. 5 is a similar view of an apparatus designed forrelease of free explosive, and

Fig. 6 is a similar view of a modified'form of the apparatus of Fig. 5.

In the drawing, in which like reference characters indicate like parts, Fig. 1 shows one form of the apparatus installed in a well Il) provided with a casing Il. According to the invention there is provided a container shell I2 adapted to contain a charge of explosive i3, usually solidied nitroglycerine, and having a closure or shell retaining member I4 shown in detail in Fig. 2. The shell and closure are lowered into the well by means of a cable l5 attached through a coupling member I6 to supporting members I1 for the closure as shown. The cable passes over a supporting pulley 20 and thence to a reel 2| actuated by a pulley 22 and suitable power means, not shown. A depth indicator 23 of conventional construction indicates the amount of cable reeled out. The cable contains two electric wires 24 and 25. Current is applied to these wires through the agency of two slip rings 26 and 21 on the reel, to which connection is made by two brushes 28 and 29 in circuit with a battery 36, a push button type switch 3| and an indicating instrument 32. Instead of the battery any other suitable source of current can be employed.

Referring to Fig. 2, the closure I4 contains a pair of latch members 33 urged inwardly by springs 34 and engaging corresponding cavities 35 in the upper thickened annular portion 36 of container I2. The two latch members are retained in position shown while the apparatus is plunger 38 extending into a solenoid coil 39 supl plied directly by leads 24 and 25 as shown. Upon energization of the solenoid, by closing switch 3|, the links are pulled up past the center point so that springs 34 withdraw the latch members and release the container shell. The closure can then be drawn out of the well. To attach a new container shell 'to the closure, the closurer is fitted on the shell and the latches are locked by reversing the solenoid coil current or by simply pushing down plunger 38.

Advantageously there is provided means for showing at the surface of the earth when the container has been released. These take the form of a small pin 46 retained in a bore 4| in the closure and resting on the lip of annulus 36. The pin is normally out of contact with a contact member 42 insulatedly supported at 43 on the closure. The pin and the contact member are connected in parallel with the solenoid by leads 45. Thus when the container shell leaves the closure, leads 24 and 25 are shortcircuited and this is exhibited by indicating instrument 32, as the resistance of the electrical circuit is less than when the solenoid is in circuit.

Fig. 3 shows a modified form of releasing device, applied to a closure |I4. A plurality of solenoid coils 46 are provided (only one is shown) each having a cooperating plunger 41 with a latch portion 48 extending through the closure into cavities 49 in annulus 36. Upon energization of the solenoids the container is released.

Fig. 4'shows another Inodication, in which the hot wire principle is employed. A plurality of latch members 56 are provided, extending into cavities 49 as in Fig. 3 and urged inwardly, by springs 34. The latch member is normally held outward by a bell-crank lever pivoted to a fixed portion of the closure at 52 and having a roller 53 at its outer end engaging the`rounded end 54 of the latch member. The lever rests on a stop 55 as shown and its opposite end is held in position, against the force of a spring 56, by a metal wire 51 adapted to expand on passage of a heating current therethrough. The wire is insulated from the lever at 58 and is supported 'through insulation 59 in a support 60 in the closure. Leads 24 and 25 are connected to spaced points on the wire. On energization of the leads the Wire expands and lever 5| flies upwardly, releasing the latch.

Figs. 5 and 6 show a form `of the invention adapted for releasing explosive directly into the well. As shown; a container 65 is provided, at-l lmember 56 of construction similar to the latch member in Fig. 4 and engaging a cavity 68 near the lower edge of the container. The latch mem. ber is normally retained in the position shown by a lever 69 pivoted to the closure member at 10 and having a roller 1I engaging the end of the latch member. A release is provided including a rotatable member 12 pivoted to the closure member at 13 and having a 'detent portion 14 loosely engaging the endof lever 69. Member 12 normally rests on a small support 15 o'n the closure. It is pivotally attached at 16 to a solenoid plunger 11 working in a solenoid coil 18 energized by wires 24 and 25. A mercury switch 19 is provided as shown, so connected that upon dropping of the closure the switch shortcircuits leads 24 4and 25 so as to indicate at the top of the well that the closure has dropped. In Fig. 6 a simplified arrangement is provided, including a latch member 50 similar to the latch member of Fig. 4, normally retained in the `position shown by a soft-iron lever |5I carrying a roller 53 and pivoted at 80 to the closure member 8|.

The lever is adapted to release the latch member' can be Withdrawn intact and appropriate steps taken to remove the obstruction. The apparatus is embodied in the usual materials for oil well apparatus, such as steel and brass, and the cable can be of a conventional type used for lowering electrical well surveying apparatus and the like. Various types of explosives can be handled. For the sake of clarity the drawing is quite diagrammatic. The provision of suitable gaskets, sealing means, etc., to prevent leakage of the explosive is within the expected skill of those familiar with the art.

The explosive 4after being positioned according to the invention is exploded in any suitable manner, as by lowering a time bomb upon it, or dropping a weight, etc. Ordinarily a solid form of explosive is employed.

What I claim is:

1.An apparatus for'placing a charge of explosive in a `well under positive control from the I top of the well comprising an explosive container of cross section such as to permit passage in a well and having an opening at one end of substantially the same area as the internal cross section of the container, a closure for the container opening, electrically operable latch means within` the closure arranged to normally retain the closure in closed relation to the container,

l cable means constructed and arranged to suspend the container in a Well, a source of electrical energy in circuit with the electrically operable latch means and circuit control mea-ns includingleads extending u p the cable and operable at the top of the well for-controlling application of electrical energy to the latch means.

2. The apparatus of claim 1 wherein the container opening is at the bottom thereof whereby on release of the latch means the explosive chalrge is discharged from the container` into the we 3. The apparatus of claim l wherein the contop of the well comprising an explosive container of cross section such as to permit passage in a well, cable means constructed and arranged to suspend the container in a well, a releasable holding member for coupling` the explosive charge in said container to the cable means, electrical operable latch means associated with said holding member and normally positively engaging said container but operating under electrical energy to permit positive release of said explosive charge from said cable means, a source of electrical energy in circuit with the electrical operable latch means and circuit control means including leads extending up the cable and operable at the top of the well for controlling application of the electrical energy to the latch means.

GORDON C. MACDONALD. 

